start (actual) email auth, add CancellationToken to most async methods

Foxnouns.Backend/Config.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using Serilog.Events;
 
 namespace Foxnouns.Backend;
@@ -15,6 +16,7 @@ public class Config
     public LoggingConfig Logging { get; init; } = new();
     public DatabaseConfig Database { get; init; } = new();
     public StorageConfig Storage { get; init; } = new();
+    public EmailAuthConfig EmailAuth { get; init; } = new();
     public DiscordAuthConfig DiscordAuth { get; init; } = new();
     public GoogleAuthConfig GoogleAuth { get; init; } = new();
     public TumblrAuthConfig TumblrAuth { get; init; } = new();
@@ -46,6 +48,12 @@ public class Config
         public string Bucket { get; init; } = string.Empty;
     }
 
+    public class EmailAuthConfig
+    {
+        public bool Enabled => From != null;
+        public string? From { get; init; }
+    }
+
     public class DiscordAuthConfig
     {
         public bool Enabled => ClientId != null && ClientSecret != null;